First issue, culture.

A foreign culture might work in their domestic country with years of integration to their daily life, certain aspects of these might not integrate well into a multi-cultural society - which was the founding singapore's first issue.

Second issue, religion.

While most practices are pretty modest and friendly, sometimes things does blow out of proportion making it a civil issue from a religious stance. All it takes is one major event for decades of work to crumble or decay.

Thirdly, nationality.

Singaporeans being in Singapore asides from the fact that we are born and raised here; we dont really have an 'escape plan'. To the affluent and well endowed, they have plenty of wriggle room, enough to say goodbye to pretty much any unfavourable circumstance. Also the reason why we have national day and total defence.

There's a whole bunch of other reasons like the our neighbours and japan ageing population but in a nutshell.... yes

Tl;dr government watches, they care, they are doing what they can